Conventionally, there are known image forming apparatuses that have, as a power supply mode, a normal mode and a power saving mode in which electric power consumption is suppressed compared to in the normal mode. A conventional image forming apparatus is provided with a plurality of sensing portions that change levels of output signals according to the status of the image forming apparatus. For example, the sensing portions provided in the image forming apparatus include a document set sensing portion of which the level of the output signal changes when a document to be read is set on the image forming apparatus, a cassette sensing portion of which the level of the output signal changes when the sheet cassette of the image forming apparatus is attached or detached, and a cover sensing portion of which the level of the output signal changes when the cover that is openably and closably fitted to the image forming apparatus is opened or closed.
The conventional image forming apparatus returns to the normal mode, for example, when the level of the output signal of the document set sensing portion changes during the period of the power saving mode. Here, an operation panel of the image forming apparatus shows a setting screen for accepting settings related to a job (for example, see Patent Document 1). With this, when a user tries to execute a job involving document reading (such as a copy job), even if the image forming apparatus is in the power saving mode, simply setting a document on the image forming apparatus causes the image forming apparatus to return to the normal mode (causes the setting screen to be displayed on the operation panel), and this is convenient for the user.